We will continue our studies on the organization and expression of the gene family of pancreas-specific serine protease by addressing the following three specific aims: (1) Using cloned mRNA sequences that we have obtained for several rat pancreatic serine proteases, we will (a) obtain, via recombinant DNA techniques, cloned genomic fragments bearing serine protease genes, (b) position the genes within those fragments, (c) define the 5' and 3' limits of the genes, (d) determine the number and position of intervening sequences within each gene, (e) and compare 5' flanking sequences for interesting regions of homology. (2) We will map several serine protease genes to individual chromosomes, to determine whether they are linked or scattered throughout the genome. (3) In order to assess the degree of coordinate expression of the pancreatic serine protease gene family during development, we will monitor the accumulation of several serine protease mRNAs during pancreogenesis.